Stepping motor drive and stepping motor driving method

ABSTRACT

In a drive of a stepping motor, an electromotive force is generated on the coil of a motor with a sinusoidal wave having the same period as an energization period by smoothly rotating a rotor with microstep driving, and an induced power is stably detected by detecting the electromotive force at the zero cross of driving current. The detection around the current zero cross makes it possible to shorten a detection section, form a driving waveform with few distortions, and perform driving with a driving waveform as in an ordinary micro step. Thus a circuit is provided which is aimed at reducing noise, vibrations, and loss of synchronization, and increasing current consumption efficiency in the determination of stop.

FIELD OF THE INVENTION

The present invention relates to a stepping motor drive and a steppingmotor driving method, and particularly relates to a stepping motor driveand a stepping motor driving method which determine whether an opticalpickup is stopped or not in an optical disk device.

BACKGROUND OF THE INVENTION

Conventionally, before reading or writing data in an optical diskdevice, it is necessary to read disk information on the innermost end ofa disk after power is turned on. However, an optical pickup is notalways placed on a predetermined point because of disturbance. Thus theoptical pickup is moved to one of the outermost end and the innermostend of the disk to adjust the offset of the position of the opticalpickup, and then a reading sequence is started. In this movement to oneof the outermost end and the innermost end, an optical sensor and acontact switch have been used to detect arrival at a destination.However, these components are more expensive than motor driver ICs. Inorder to reduce the cost of the overall optical disk device, a stopdetermination function is provided for the motor driver IC of a steppingmotor and components required as detectors have been reduced. It isdetected that an induced voltage is not outputted when the opticalpickup reaches the innermost end and the outermost end, the opticalpickup is made unmovable by a stop member, and the rotor of the steppingmotor is locked. Further, the occurrence of an induced voltage in anormal rotation is detected. In the prior art, however, the detection ofan induced voltage requires a high impedance section in an energizationpattern and affects an energization waveform, causing a loss ofsynchronization of the rotor, vibrations, noise, and higher powerconsumption.

A technique relating to the present invention is, for example, describedas a patent document in JP2005-27370A2. In order to detect the state ofa rotor, a detection state setting unit is provided for setting adetection state in which one motor coil of two phases is cut off whenthe other coil can be energized, an induced voltage detecting unit isprovided for detecting the induced voltage of the one coil, and a rotorstate determination unit for determining the state of the rotor based onthe detected induced voltage. With this configuration, the state of therotor is determined based on the state of the induced voltage which isgenerated during the movement of the rotor.

DISCLOSURE OF THE INVENTION

The present invention provides, in an optical disk device, a circuit anda method for detecting the non-rotational state of a rotor based on achange of an induced voltage generated on a coil for driving a steppingmotor, in the case where the stepping motor rotates which serves as apower source of a mechanism for moving an optical pickup by the rotationof a feed screw, the optical pickup is moved to one of the innermost endand the outermost end of a disk, reaches the end of a movable range, andis made unmovable by a member interrupting the movement of the opticalpickup on the end of the movable range, and the rotor of the linkedstepping motor enters the non-rotational state.

Further, in order to detect a change of current and voltage of inducedpower on a coil to be detected in the prior art, sufficient time isnecessary for the discharge of applied current and a sequence ofrepeating detection several times, and an exciting method is limited tofull-step driving, half-step driving, and so on. Although a microstepmethod is available, detection requires a high-impedance output for arelatively long period. A high-impedance section deforms a load currentwaveform and forms a driving waveform for each phase, so that noise andvibrations may occur on a stepping motor and a rotor is likely to losesynchronization. Moreover, such a method causes large power consumptionand low efficiency, so that driving with an ideal microstep waveform isimpossible in the determination of stop.

In the present invention, an electromotive force is generated on thecoil of a motor with a sinusoidal wave having the same period as anenergization period by smoothly rotating a rotor with microstep driving,and an induced power is stably detected by detecting the electromotiveforce at the zero cross of driving current. The present inventionprovides a circuit and a method which are aimed at reducing a detectionsection through detection around the zero cross of current, forming adriving waveform with few distortions, and performing driving with adriving waveform as in an ordinary microstep method. Further, thecircuit and the method are aimed at reducing noise, vibrations, and lossof synchronization, and increasing current consumption efficiency in thedetermination of stop.

In order to attain the object, an induced voltage is detected around thezero cross of a coil current at the switching of the direction of thecoil current, and the timing is generated from an input command levelcorresponding to the zero cross of the coil current.

The present invention can suppress the distortions of an energizationwaveform of a stepping motor and enable the stop determination of arotor. By reducing distortions, it is possible to reduce vibrations,noise, loss of synchronization, and power consumption which adverselyaffect stop determination in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory drawing showing the embodiment of claim 1, 2and 13;

FIG. 2 is an explanatory drawing showing 120 and 130 of FIG. 1;

FIG. 3 is an input/output waveform chart of FIG. 1;

FIG. 4 is an explanatory drawing showing the embodiment of claim 3, 4and 14;

FIG. 5 is an explanatory drawing showing 120 and 130 of FIG. 4;

FIG. 6 is an input/output waveform chart of FIG. 5;

FIG. 7 is an explanatory drawing showing the embodiment of claim 5, 6and 15;

FIG. 8 is an input/output waveform chart of FIG. 7;

FIG. 9A and FIG. 9B are a waveform chart around the dead zone of anoutput current feedback method and a waveform chart around the dead zoneof voltage driving;

FIG. 10 is an explanatory drawing showing the embodiment of claim 7, 8and 16;

FIG. 11 is the input/output waveform chart of FIG. 10;

FIG. 12 is a waveform chart around the dead zone of FIG. 11;

FIG. 13 is an explanatory drawing showing the embodiments of claim 7, 9and 10; and

FIG. 14 is an explanatory drawing showing the embodiments of claims 7,9, 10, 11 and 12.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is an explanatory drawing showing the embodiment of claim 1 and13. In FIG. 1, reference numeral 300 denotes a two-phase bipolarstepping motor. An A-phase input signal and a B-phase input signal arefed with an analog signal having one of a sinusoidal wave and atriangular wave with a phase shift of 90° and digital information. In anA-phase output unit (120) and a B-phase output unit (220), the powertransistors of one of the output units are driven so as to output avoltage or current obtained by multiplying the values of the A-phaseinput signal and the B-phase input signal by an optionally set gain.

FIG. 2 shows an example of the configuration of the driven powertransistor. FIG. 2 shows an H-bridge configuration for PWM driving.Diodes (41, 42, 43, 44) for regeneration are provided on a power supplyand the ground from an output terminal connected to a motor coil (31).Power transistors (21, 22, 23, 24) are driven through pre-drives (10,11). The power transistors have the function of obtaining a highimpedance in response to a signal from a detection control unit (310)regardless of the state of an input signal. When an output has a highimpedance, a current in the motor coil (31) rapidly increases a voltageacross the coil because of the inductance of the coil, the current isregenerated on the power supply and the ground by the diodes (41, 42,43, 44), and the current in the motor coil (31) disappears.

An A-phase current zero-cross detection unit (130) and a B-phase currentzero-cross detection unit (230) which detect a current zero cross arerespectively inserted between the output of the A-phase output unit(120) and the coil of a motor and between the output of the B-phaseoutput unit (220) and the coil (31) of a motor. The A-phase currentzero-cross detection unit (130) and the B-phase current zero-crossdetection unit (230) output detection results of zero cross to thedetection control unit (310). The detection control unit (310) performsa sequence of detecting an induced voltage. One of the A-phase andB-phase output units is made up of an H bridge including the powertransistors (21, 22, 23, 24) and the diodes for regeneration (41, 42,43, 44) and the pre-drives for directly driving the power transistors.One of the A-phase and B-phase current zero-cross detection units ismade up of a resistor (51) inserted between the output terminals of theH bridge in series with the coil (31) of the motor, and a currentdirection detecting comparator (52). Both ends of the resistor areconnected to the inverting input and the non-inverting input of thecomparator, an edge at which the output of the comparator is switched isthe timing of the current zero cross of the coil (31), and a signalindicating a direction switched at an edge of a square wave can beoutputted.

FIG. 3 shows an input signal, a detection control signal, a coildifference voltage, a load current, and an induced voltage of each phaseand further shows the rotation speed of a rotor and the logic of stopdetermination output according to the embodiment. In FIG. 3, when asignal indicating the timing of detection is inputted at a rising edgeand a falling edge to one of an output signal (131 a) of the A-phasecurrent zero-cross detection unit and the output signal (231 a) of theB-phase current zero-cross detection unit, the detection control unit(310) transmits a command for obtaining a high impedance output for acertain time to the output unit (120, 220) of the phase to be detected.When one phase has a high impedance, the current of the coil isregenerated as has been discussed, so that the current becomes zero.Even when one phase has a zero current, the current value of the otherphase keeps changing and the rotor keeps rotating by the inertia of therotor in microstep driving. A distance between the permanent magnet ofthe rotor and the coil changes and an induced voltage is generated. Theinduced voltage generates a voltage having a sinusoidal wave with thesame period as an energization period in synchronization with the phaseof the rotor. When the rotor is completely stopped, a distance betweenthe permanent magnet of the rotor and the coil does not change. Thus theinduced voltage is not generated. When the rotor is brought into contactwith a stop member with an impact, the rotor moves back in an actualoperation. Thus an induced voltage is generated in a different directionfrom the direction of an actual induced voltage. One of an A-phaseinduced voltage detection unit (140) and a B-phase induced voltagedetection unit (240) detects the generation of an induced voltage. Thedetection control unit (310) instructs the induced voltage detectionunit (140, 240) of the phase to be detected, about the timing ofdetection and a direction along which the induced voltage is generated.The induced voltage detection unit (140, 240) detects the directionalong which the induced voltage is generated and detects whether or notthe absolute value of the induced voltage exceeds a predeterminedthreshold value, and outputs the result to a stop determination unit(320). The stop determination unit (320) updates a stop determinationresult in each energization period of 90°. The result of one of theinduced voltage detection units (140, 240) is updated every time thedetection control signal is generated, so that a determination resultcan be obtained with high responsiveness. As the coil has a largernumber of phases, the stop determination result is updated at shorterintervals. Moreover, a circuit size can be reduced by reducing thenumber of detected phases and increasing an interval between updates.

As an embodiment of claim 2, 4, 6, 8, 10 and 12, a determination aboutwhether the rotor is stopped or rotated is outputted based on aplurality of results from an induced voltage detection unit. Forexample, when it is determined that the rotor is stopped, the state isrecorded. When it is determined again that the rotor is stopped at thesubsequent determination update in which a rotation is kept, a stopsignal is not outputted to a stop determination output until it isdetermined that the rotor is stopped for two consecutive times. The stopsignal can be outputted also after more determinations or when at leasta predetermined number of stops are determined in a period. Theplurality of results from the induced voltage detection unit make itpossible to achieve stop determination with higher reliability.

As shown in FIG. 3, as a detection position, an output current at thezero cross has the largest induced voltage and is the most effectiveagainst noise and an induced voltage resonance reduced by resonance. Theamplitude of the generated induced voltage is substantiallyproportionate to the number of revolutions. The larger number ofrevolutions, the higher induced voltage. The threshold value is set inconsideration of the number of revolutions and an allowance for a phaseshift.

Further, since a high impedance output can be obtained when the outputcurrent is zero, the distortions of waveforms can be minimized andefficient driving can be performed. When a high impedance output isobtained while the output current remains, detection has to be performedwith the high impedance until the current is completely regenerated.Thus as the output current increases, a longer time is necessary for thehigh impedance. Switching to the high impedance at the current zerocross can shorten a high impedance time, reduce a non-conducting time,and suppress the distortions of an output waveform.

FIG. 4 is an explanatory drawing showing the embodiment of claim 3, 4and 14. An A-phase current zero-cross detection unit (131) and a B-phasecurrent zero-cross detection unit (231) which detect a current zerocross according to a clipped voltage during regeneration are connectedto one output of an A-phase motor coil and one output of a B-phase motorcoil, respectively. The A-phase current zero-cross detection unit (131)and the B-phase current zero-cross detection unit (231) output detectionresults of zero cross to a detection control unit (310). The detectioncontrol unit performs, as in the embodiment of FIG. 1, a sequence fordetecting an induced voltage. FIG. 5 is an explanatory drawing of theA-phase current zero-cross detection unit (131) and the B-phase currentzero-cross detection unit (231). When PWM driving of both choppingmethod is performed in an H-bridge circuit shown in FIG. 5, outputs Vaand Vb connected to both ends of a coil (31) alternately repeat L outputand H output. When a difference in voltage between Va and Vb appears,the coil is energized. Usually, an output current is smoothed byperforming PMW driving with a sufficiently shorter period than a timeconstant determined by the inductance and the resistance value of thecoil of a motor. The smoothed current has a phase delayed from the phaseof the mean value of an output voltage by the time constant determinedby the inductance and the resistance value of the coil. When the outputsVa and Vb change from L output to H output and from H output to Loutput, PWM driving requires a dead-time period during which a powertransistor on a power supply and a power transistor on the ground aresimultaneously turned on and then both of the transistors are turned offso as not to generate a flow-through current. When the output is in thedead-time period, a current is regenerated through a diode. When thecurrent is regenerated on the power supply, the output has the potentialof a power supply voltage plus the forward voltage of the diode. Whenthe current is regenerated on the ground, the potential is lower than aground potential by the forward voltage of the diode. FIG. 6 shows theoutput waveform of the power transistor around the current zero cross,the output waveforms of comparators, and the output signal of currentzero-cross stop determination. The current zero-cross detection unitmonitors Va and Vb and a clamping voltage generated by regeneration isdetected by comparators (61, 62). The comparators (61, 62) for detectingregeneration output output results Vc and Vd to an R-S flip-flop (63).By changing the direction of current, a detection output is switchedfrom the comparator (61) on the power supply to the comparator (62) onthe ground. An output Ve of the R-S flip-flop (63) indicates thedirection of current, and rising and falling edges indicate the timingof switching directions. The current zero-cross detection unit outputsthe timing of zero cross to the detection control unit, and thedetection control unit (310) performs the sequence for detecting aninduced voltage as in the embodiment of FIG. 1.

FIG. 7 is an explanatory drawing showing the embodiment of claim 5, 6,and 15. As in the embodiment of FIG. 1, reference numeral 300 denotes atwo-phase bipolar stepping motor. To an A-phase input signal and aB-phase input signal, an analog signal having one of a sinusoidal waveand a triangular wave with a phase shift of 90° and digital informationare inputted. An A-phase output unit (120) and a B-phase output unit(220) drive power transistors so as to output a current obtained bymultiplying the values of the A-phase input signal and the B-phase inputsignal by a optionally set gain.

FIG. 8 shows, according to the embodiment of claim 5, 6 and 15, an inputsignal of each phase, an input threshold value of each phase, the outputsignal of the comparator of each phase, a voltage difference betweencoil terminals, a load current, an induced voltage, the rotation speedof a rotor, and the logic of stop determination output. The A-phaseinput signal and an A-phase input threshold value are compared with eachother by an A-phase comparator (150) and are outputted as a binaryoutput signal (150 a). A B-phase input threshold value is compared by aB-phase comparator (250) and is outputted as a binary output signal (250a). The two output signals (150 a, 250 a) are inputted to a detectioncontrol unit (310). At the rising and falling edges of the two outputsignals (150 a, 250 a), a signal is transmitted to have a high-impedanceoutput for a certain time from the output unit (120, 220) of a phase tobe detected. A previous input command comes close to zero at this momentand the current of a coil comes close to zero, though a small amount ofthe current remains. Thus when a phase has a high impedance, the currentof the coil is regenerated and completely becomes zero in a short time.

FIG. 9A shows, around an input zero cross, the waveforms of the inputsignal, a load current, and a difference in voltage between an output Vaterminal and an output Vb terminal when a high-impedance output isobtained at the input zero cross according to a current driving method.When the driving method uses output current feedback, an input commandand an output current are in phase with each other. Thus the timing ofthe input zero cross and the timing of the zero cross of output currentare synchronized with each other. By setting the A-phase input thresholdvalue and the B-phase input threshold value at the zero position of aninput waveform, a rectification time by regeneration can be minimized.Thus a high impedance required for detection can be also shortened, sothat the detection can be performed in a short time. Moreover, thehighest induced voltage can be detected and thus a rotating state and anon-rotating state can be easily distinguished from each other. Thus thezero cross of output current is not directly detected. When an inputvalue is zero, the timing of the zero cross of output current isobtained based on the input value obtained through feedback.Consequently, the detection can be performed in a short time and thesame effects as the configurations of FIGS. 1 and 4 can be obtained.

FIG. 9B shows, around the input zero cross, the waveforms of the inputsignal, a load current, and a difference in voltage between the outputVa terminal and the output Vb terminal when a high-impedance output isobtained at the input zero cross in voltage driving. At the input zerocross of voltage driving, the phase of current is delayed by theinductance of a coil (31) and the time constant of a resistancecomponent. When a high-impedance output is obtained at the timing of theinput zero cross, an amount of current passing through the coil (31) isnot sufficiently small and a time period until a load current becomeszero by regeneration has to be sufficiently long as compared withcurrent feedback. Insufficient high-impedance time cannot enableaccurate measurements but a long high-impedance section distorts anenergization waveform, so that it is impossible to reduce vibrations andnoise and prevent loss of synchronization.

FIG. 10 is an explanatory drawing showing the embodiment of claim 7, 8and 16. In the embodiment of FIG. 10, the output signals (Vg, Vh) of anA-phase comparator and a B-phase comparator are respectively inputted toan A-phase signal delay unit (160) and a B-phase signal delay unit (260)which can delay the signals by a predetermined time, and delay resultsare inputted to a detection control unit (310). As illustrated in FIG.9B, the phase of a current waveform is delayed by the inductance of amotor and a resistance component and the timing of the zero cross ofoutput current is considerably delayed by the phase delay. In FIG. 10,by delaying the signals in the A-phase signal delay unit (160) and theB-phase signal delay unit (260), detection is performed at the zerocross of output current. FIG. 11 shows the signal timing of Vg, Vh, Viand Vj and the relationship between an input/output and an inducedvoltage. FIG. 12 is an enlarged view around the zero cross of an inputsignal. By delaying the timing of switching to a high impedance by thedelay of the zero cross of a load current, the timing of the zero crossof an input signal can be switched when the load current is zero. Thus ahigh-impedance time can be shortened, so that distortions can besuppressed and detection can be performed in a short time.

FIG. 13 is an explanatory drawing showing the embodiment of claim 7, 9,and 10. The timing delay of an input zero cross can be adjusted inresponse to a signal from the inside or the outside of a circuit, sothat it is possible to respond to fluctuations in delay time. The delaytime changes with surrounding conditions such as a load of a coil and aninput waveform.

FIG. 14 is an explanatory drawing showing the embodiments of claims 7,9, 10, 11 and 12. Discharge by the regeneration of a load current is notalways completely switched at zero current, and a discharge time ofcurrent is actually necessary. When the load of a coil is changed bychanging stepping motors or when surrounding conditions are changed, thedischarge time fluctuates. A state is optimized by changing ahigh-impedance time in response to a signal from the inside or outsideof a circuit. This configuration can prevent erroneous detection whichis caused by a residual coil current because of an insufficienthigh-impedance time as shown in FIG. 9B. When the high-impedance time islonger than necessary, a driving waveform with few distortions can beobtained by eliminating an excessive high-impedance time.

The present invention can reduce the possibility of noise, vibrations,and loss of synchronization, efficiently rotate a stepping motor, anddetermine whether a rotor is stopped or not. The present invention isparticularly applicable to a drive of a stepping motor for determiningwhether an optical pickup is stopped or not in an optical disk device.Further, the present invention is applicable to a drive of a steppingmotor as a resetting operation to the zero position of an analoginstrument and the like.

1. A drive of a stepping motor having driving coils of multiple phases(N≧2), the drive comprising: output units of multiple phases (N≧2), eachcomprising first and second outputs which are connected to both ends ofthe driving coil of the stepping motor and capable of outputting one ofa voltage and a current in proportionate to an input signal, a diode soconnected as to switch a state to a high impedance state in response toa high-impedance switching signal and pass a current in a forwarddirection from the first and second outputs to a first power supply, anda diode so connected as to pass a current in the forward direction froma second power supply to the first and second outputs, the first powersupply keeping a higher potential than the second power supply, theoutput unit regenerating a current of a motor coil when the first andsecond outputs have high impedances; circuits of 1 to N phases, eachcomprising a current zero-cross detection unit for detecting, by meansof a current detecting resistor inserted between the driving coil andthe first output, a zero cross at which positive and negative directionsof a load current are switched, and outputting an induced voltagedetection timing signal, and an induced voltage detection unit which isconnected to both ends of the driving coil of the stepping motor,detects an induced voltage in response to a detection start signal ofthe induced voltage, and outputs a detection result signal; a detectioncontrol unit for outputting the high-impedance switching signal to theoutput unit in response to the induced voltage timing signal to detectthe induced voltage, and outputting the detection start signal of theinduced voltage to the induced voltage detection unit and adetermination timing signal to a stop determination unit after a certaindelay; and the stop determination unit for outputting a rotor state suchas rotation, stop, and loss of synchronization to outside every time thestop determination unit receives the latest detection result signalsfrom the induced voltage detection units of 1 to N phases and thedetermination timing signal from the detection control unit, and keepingan output until the stop determination unit receives a subsequentdetermination timing signal.
 2. The drive of the stepping motoraccording to claim 1, wherein the stop determination unit determines therotor state based on the detection result signals of the induced voltagedetection units of the multiple phases, and outputs the rotor stateincluding rotation, stop, and loss of synchronization to the outside. 3.A drive of a stepping motor having driving coils of multiple phases(N≧2), the drive comprising: output units of multiple phases (N≧2), eachcomprising first and second outputs which are connected to both ends ofthe driving coil of the stepping motor and capable of outputting one ofa voltage and a current in proportionate to an input signal, a diode soconnected as to switch a state to a high impedance state in response toa high-impedance switching signal and pass a current in a forwarddirection from the first and second outputs to a first power supply, anda diode so connected as to pass a current in the forward direction froma second power supply to the first and second outputs, the first powersupply keeping a higher potential than the second power supply, theoutput unit regenerating a current of a motor coil when the first andsecond outputs have high impedances; circuits of 1 to N phases, eachcomprising a current zero-cross detection unit for detecting a clampingvoltage generated during current regeneration of the driving coil,detecting a time when positive and negative directions of a currentoutputted from the output unit are switched, and outputting an inducedvoltage detection timing signal of the driving coil, and an inducedvoltage detection unit which is connected to both ends of the drivingcoil of the stepping motor, detects an induced voltage in response to adetection start signal of the induced voltage, and outputs a detectionresult signal; a detection control unit for outputting thehigh-impedance switching signal to the output unit in response to theinduced voltage timing signal to detect the induced voltage, andoutputting the detection start signal of the induced voltage to theinduced voltage detection unit and a determination timing signal to astop determination unit after a certain delay; and the stopdetermination unit for outputting a rotor state such as rotation, stop,and loss of synchronization to outside every time the stop determinationunit receives the latest detection result signals from the inducedvoltage detection units of 1 to N phases and the determination timingsignal from the detection control unit, and keeping an output until thestop determination unit receives a subsequent determination timingsignal.
 4. The drive of the stepping motor according to claim 3, whereinthe stop determination unit determines the rotor state based on thedetection result signals of the induced voltage detection units of themultiple phases, and outputs the rotor state including rotation, stop,and loss of synchronization to the outside.
 5. A drive of a steppingmotor having driving coils of multiple phases (N≧2), the drivecomprising: output units of multiple phases (N≧2), each comprising firstand second outputs which are connected to both ends of the driving coilof the stepping motor and capable of outputting one of a voltage and acurrent in proportionate to an input signal, a diode so connected as toswitch a state to a high impedance state in response to a high-impedanceswitching signal and pass a current in a forward direction from thefirst and second outputs to a first power supply, and a diode soconnected as to pass a current in the forward direction from a secondpower supply to the first and second outputs, the first power supplykeeping a higher potential than the second power supply, the output unitregenerating a current of a motor coil when the first and second outputshave high impedances; circuits of 1 to N phases, each comprising acomparator for comparing the input signal with one of an input fromoutside of the drive and a threshold value set in the drive, andoutputting an output result as an induced voltage detection timingsignal, and an induced voltage detection unit which is connected to bothends of the driving coil of the stepping motor, detects an inducedvoltage in response to a detection start signal of the induced voltage,and outputs a detection result signal; a detection control unit foroutputting the high-impedance switching signal to the output unit inresponse to the induced voltage timing signal to detect the inducedvoltage, and outputting the detection start signal of the inducedvoltage to the induced voltage detection unit and a determination timingsignal to a stop determination unit after a certain delay; and the stopdetermination unit for outputting a rotor state such as rotation, stop,and loss of synchronization to the outside every time the stopdetermination unit receives the latest detection result signals from theinduced voltage detection units of 1 to N phases and the determinationtiming signal from the detection control unit, and keeping an outputuntil the stop determination unit receives a subsequent determinationtiming signal.
 6. The drive of the stepping motor according to claim 5,wherein the stop determination unit determines the rotor state based onthe detection result signals of the induced voltage detection units ofthe multiple phases, and outputs the rotor state including rotation,stop, and loss of synchronization to the outside.
 7. A drive of astepping motor having driving coils of multiple phases (N≧2), the drivecomprising: output units of multiple phases (N≧2), each comprising firstand second outputs which are connected to both ends of the driving coilof the stepping motor and capable of outputting a voltage inproportionate to an input signal, a diode so connected as to switch astate to a high impedance state in response to a high-impedanceswitching signal and pass a current in a forward direction from thefirst and second outputs to a first power supply, and a diode soconnected as to pass a current in the forward direction from a secondpower supply to the first and second outputs, the first power supplykeeping a higher potential than the second power supply, the output unitregenerating a current of a motor coil when the first and second outputshave high impedances; circuits of 1 to N phases, each comprising acomparator for comparing the input signal with one of an input fromoutside of the drive and a threshold value set in the drive, andoutputting an output result as an induced voltage detection timingsignal, a signal delay unit for delaying the induced voltage detectiontiming signal from the comparator and outputting an induced voltagedetection delay timing signal, and an induced voltage detection unitwhich is connected to both ends of the driving coil of the steppingmotor, detects an induced voltage in response to a detection startsignal of the induced voltage, and outputs a detection result signal; adetection control unit for outputting the high-impedance switchingsignal to the output unit in response to the induced voltage timingsignal to detect the induced voltage, and outputting the detection startsignal of the induced voltage to the induced voltage detection unit anda determination timing signal to a stop determination unit after acertain delay; and the stop determination unit for outputting a rotorstate such as rotation, stop, and loss of synchronization to the outsideevery time the stop determination unit receives the latest detectionresult signals from the induced voltage detection units of 1 to N phasesand the determination timing signal from the detection control unit, andkeeping an output until the stop determination unit receives asubsequent determination timing signal.
 8. The drive of the steppingmotor according to claim 7, wherein the stop determination unitdetermines the rotor state based on the detection result signals of theinduced voltage detection units of the multiple phases, and outputs therotor state including rotation, stop, and loss of synchronization to theoutside.
 9. The drive of the stepping motor according to claim 7,further comprising a delay time setting unit for controlling a delayamount set in response to an input from the outside of the drive or setin the drive, wherein the signal delay unit is provided with a functionof changing delay in response to a command from the delay time settingunit.
 10. The drive of the stepping motor according to claim 9, whereinthe stop determination unit determines the rotor state based on thedetection result signals of the induced voltage detection units of themultiple phases, and outputs the rotor state including rotation, stop,and loss of synchronization to the outside.
 11. The drive of thestepping motor according to claim 7, further comprising a high-impedancetime setting unit for controlling a high impedance time according to oneof an input from the outside of the drive and a value set in the drive,wherein the detection control unit is provided with a function ofchanging a time setting of a high impedance period according to an inputfrom the outside of the drive in response to the high impedanceswitching signal as an output.
 12. The drive of the stepping motoraccording to claim 11, wherein the stop determination unit determinesthe rotor state based on the detection result signals of the inducedvoltage detection units of the multiple phases, and outputs the rotorstate including rotation, stop, and loss of synchronization to theoutside.
 13. A method of driving a stepping motor having driving coilsof multiple phases (N≧2), comprising the steps of: configuring outputunits of multiple phases (N≧2), each comprising first and second outputswhich are connected to both ends of the driving coil of the steppingmotor and capable of outputting one of a voltage and a current inproportionate to an input signal, a diode so connected as to switch astate to a high impedance state in response to a high-impedanceswitching signal and pass a current in a forward direction from thefirst and second outputs to a first power supply, and a diode soconnected as to pass a current in the forward direction from a secondpower supply to the first and second outputs, the first power supplykeeping a higher potential than the second power supply, the output unitregenerating a current of a motor coil when the first and second outputshave high impedances; configuring circuits of 1 to N phases, eachcomprising a current zero-cross detection unit for detecting, by meansof a current detecting resistor inserted between the driving coil andthe first output, a zero cross at which positive and negative directionsof a load current are switched, and outputting an induced voltagedetection timing signal, and an induced voltage detection unit which isconnected to both ends of the driving coil of the stepping motor,detects an induced voltage in response to a detection start signal ofthe induced voltage, and outputs a detection result signal; andconfiguring a detection control unit for outputting the high-impedanceswitching signal to the output unit in response to the induced voltagetiming signal to detect the induced voltage, and outputting thedetection start signal of the induced voltage to the induced voltagedetection unit and a determination timing signal to a stop determinationunit after a certain delay, and the stop determination unit foroutputting a rotor state such as rotation, stop, and loss ofsynchronization to outside every time the stop determination unitreceives the latest detection result signals from the induced voltagedetection units of 1 to N phases and the determination timing signalfrom the detection control unit, and keeping an output until the stopdetermination unit receives a subsequent determination timing signal.14. A method of driving a stepping motor having driving coils ofmultiple phases (N≧2), comprising the steps of: configuring output unitsof multiple phases (N≧2), each comprising first and second outputs whichare connected to both ends of the driving coil of the stepping motor andcapable of outputting one of a voltage and a current in proportionate toan input signal, a diode so connected as to switch a state to a highimpedance state in response to a high-impedance switching signal andpass a current in a forward direction from the first and second outputsto a first power supply, and a diode so connected as to pass a currentin the forward direction from a second power supply to the first andsecond outputs, the first power supply keeping a higher potential thanthe second power supply, the output unit regenerating a current of amotor coil when the first and second outputs have high impedances;configuring circuits of 1 to N phases, each comprising a currentzero-cross detection unit for detecting a clamping voltage generatedduring current regeneration of the driving coil, detecting a time whenpositive and negative directions of a current outputted from the outputunit are switched, and outputting an induced voltage detection timingsignal of the driving coil, and an induced voltage detection unit whichis connected to both ends of the driving coil of the stepping motor,detects an induced voltage in response to a detection start signal ofthe induced voltage, and outputs a detection result signal; andconfiguring a detection control unit for outputting the high-impedanceswitching signal to the output unit in response to the induced voltagetiming signal to detect the induced voltage, and outputting thedetection start signal of the induced voltage to the induced voltagedetection unit and a determination timing signal to a stop determinationunit after a certain delay, and the stop determination unit foroutputting a rotor state such as rotation, stop, and loss ofsynchronization to outside every time the stop determination unitreceives the latest detection result signals from the induced voltagedetection units of 1 to N phases and the determination timing signalfrom the detection control unit, and keeping an output until the stopdetermination unit receives a subsequent determination timing signal.15. A method of driving a stepping motor having driving coils ofmultiple phases (N≧2), comprising the steps of: configuring output unitsof multiple phases (N≧2), each comprising first and second outputs whichare connected to both ends of the driving coil of the stepping motor andcapable of outputting one of a voltage and a current in proportionate toan input signal, a diode so connected as to switch a state to a highimpedance state in response to a high-impedance switching signal andpass a current in a forward direction from the first and second outputsto a first power supply, and a diode so connected as to pass a currentin the forward direction from a second power supply to the first andsecond outputs, the first power supply keeping a higher potential thanthe second power supply, the output unit regenerating a current of amotor coil when the first and second outputs have high impedances;configuring circuits of 1 to N phases, each comprising a comparator forcomparing the input signal with one of an input from outside of a driveand a threshold value set in the drive, and outputting an output resultas an induced voltage detection timing signal, and an induced voltagedetection unit which is connected to both ends of the driving coil ofthe stepping motor, detects an induced voltage in response to adetection start signal of the induced voltage, and outputs a detectionresult signal; and configuring a detection control unit for outputtingthe high-impedance switching signal to the output unit in response tothe induced voltage timing signal to detect the induced voltage, andoutputting the detection start signal of the induced voltage to theinduced voltage detection unit and a determination timing signal to astop determination unit after a certain delay, and the stopdetermination unit for outputting a rotor state such as rotation, stop,and loss of synchronization to the outside every time the stopdetermination unit receives the latest detection result signals from theinduced voltage detection units of 1 to N phases and the determinationtiming signal from the detection control unit, and keeping an outputuntil the stop determination unit receives a subsequent determinationtiming signal.
 16. A method of driving a stepping motor having drivingcoils of multiple phases (N≧2), comprising the steps of: configuringoutput units of multiple phases (N≧2), each comprising first and secondoutputs which are connected to both ends of the driving coil of thestepping motor and capable of outputting a voltage in proportionate toan input signal, a diode so connected as to switch a state to a highimpedance state in response to a high-impedance switching signal andpass a current in a forward direction from the first and second outputsto a first power supply, and a diode so connected as to pass a currentin the forward direction from a second power supply to the first andsecond outputs, the first power supply keeping a higher potential thanthe second power supply, the output unit regenerating a current of amotor coil when the first and second outputs have high impedances;configuring circuits of 1 to N phases, each comprising a comparator forcomparing the input signal with one of an input from outside of a driveand a threshold value set in the drive, and outputting an output resultas an induced voltage detection timing signal, a signal delay unit fordelaying the induced voltage detection timing signal from the comparatorand outputting an induced voltage detection delay timing signal, and aninduced voltage detection unit which is connected to both ends of thedriving coil of the stepping motor, detects an induced voltage inresponse to a detection start signal of the induced voltage, and outputsa detection result signal; configuring a detection control unit foroutputting the high-impedance switching signal to the output unit inresponse to the induced voltage timing signal to detect the inducedvoltage, and outputting the detection start signal of the inducedvoltage to the induced voltage detection unit and a determination timingsignal to a stop determination unit after a certain delay, and the stopdetermination unit for outputting a rotor state such as rotation, stop,and loss of synchronization to the outside every time the stopdetermination unit receives the latest detection result signals from theinduced voltage detection units of 1 to N phases and the determinationtiming signal from the detection control unit, and keeping an outputuntil the stop determination unit receives a subsequent determinationtiming signal.